I would say B. Hope this helps.
I would wager to say its dette
late 13c., dette, from Old French dete, from Latin<span> debitum "thing owed," neuter past participle of debere "to owe," originally, "keep something away from someone," from de- "away" (see de-) + habere "to have" (see habit). Restored spelling after c.1400.</span>debt<span> in Medicine.</span>
Answer:
A. They also help the environment by refreshing the air and by reducing smog and effects to the ozone layer.
Explanation:
The author makes a claim that environment is refreshing by the air and the effects on ozone layer are reduced. This statement is not supported by the evidence. The ozone layer is polluted by the environment pollution. The pollution created by humans is also affecting the air which ultimately pollutes the ozone layer.